FR2794121A1 - New compositions of aromatic carboxylic acids with color developing properties in contact with a leuco dye and on application of heat, useful in the preparation of heat sensitive printing material - Google Patents

Abstract

The color developer, in combination with a leuco dye, produces color images with an improved stability towards plasticizers and oils. New compositions are claimed which comprise at least two aromatic carboxylic acids of the formulae (I), (II) and (III): X = carbonyl group ; a sulfonyl group ; a bivalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one element from a heteroatom,carbonyl, sulfonyl, an ester link and an aromatic ring ;or a bivalent group derived from an aromatic hydrocarbon prepared by linking of two aromatic hydrocarbons by he intermediary of carbonyl, sulfonyl, ester link, alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain. An Independent claim is also included for a heat sensitive print material comprising a support on which is formed the heat sensitive layer.

Description

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 The present invention relates to a composition containing aromatic carboxylic acids and which can serve as a color developer, and a thermosensitive recording material containing the aforementioned composition.

 Heat-sensitive recording materials generally comprise a support on which a thermosensitive coloring layer is formed which comprises as main components a colorless or light-colored electron donor dye precursor and an electron-accepting color developer.

The application of heat on this dye precursor and this color developer, for example by means of a thermal head, a thermal pen or a laser beam, causes their instant reaction for the production of recorded images. as disclosed in Japanese Patent Publication Nos. 43-4160 and 45-14039.

 Heat-sensitive recording materials are used in a wide variety of fields, such as recording materials for computers, fax machines, ticket machines, label printers and recorders, as they have the advantage of enabling recording with a relatively simple device, easy maintenance and no noise.

 The aforementioned heat-sensitive recording materials using such an electron donor dye precursor and such an electron acceptor color developer have excellent characteristics such as a good appearance and a pleasant feel, and they are able to produce images having a specific gravity. high staining. On the other hand, these recording materials have the disadvantage that the storage stability of recorded images is poor. More specifically, when image areas formed in the thermosensitive recording material come into contact with plastics such as polyvinyl chloride, these image areas are discolored under the effect of plasticizers and other additives contained in plastics. When the colored image areas come into contact with chemicals in foods or cosmetics, these image areas become discolored as easily or the background area easily causes the color to develop.

 To improve the storage stability of the image recorded in the thermosensitive recording material, it is conventionally proposed different very reliable chromogenic developers. For example, the use of a phenolsulfone compound as a color developer is disclosed in Japanese Patent Application Laid-Open Nos. 58-82788 and 60-13852; the use of a substituted salicylic acid compound is described in the Japanese patent application

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 subject to public inspection 65-169681. However, despite the use of the above-mentioned compounds as chromogenic developers, the image area formed in the thermosensitive recorder material still exhibits insufficient plasticizer resistance.

 A first object of the present invention is therefore to provide a color developer capable of producing colored image areas having better storage stability, particularly in terms of plasticizer resistance and oil resistance of the produced image.

 A second object of the present invention is to provide a thermosensitive recording material containing the above-mentioned color developer.

dans lesquelles X représente un groupe carbonyle ; groupe sulfonyle; un groupe bivalent dérivé d'un hydrocarbure aliphatique; un groupe bivalent dérivé d'un hydrocarbure aliphatique comprenant dans la chaîne principale au moins un élément choisi parmi un hétéroatome, un groupe carbonyle, un groupe sulfonyle, une liaison ester et un cycle aromatique ; un groupe bivalent dérivé d'un composé hydrocarboné aromatique préparé par liaison de deux hydrocarbures aromatiques par l'intermédiaire d'au moins un élément choisi parmi un hétéroatome, un groupe carbonyle, un groupe sulfonyle, une liaison ester, un alkylène et un hydrocarbure aliphatique comprenant un hétéroatome dans la chaîne principale. The first object of the present invention can be achieved by a composition containing at least two aromatic carboxylic acids selected from the group consisting of aromatic carboxylic acids having the formulas (I), (II) and (III):

in which X represents a carbonyl group; sulfonyl group; a divalent group derived from an aliphatic hydrocarbon; a divalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage and an aromatic ring; a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage, an alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain.

 In formulas (I) to (III), the divalent functional group represented by

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dans laquelle R et R', qui peuvent être identiques ou différents, sont chacun un atome d'hydrogène, un atome d'halogène, un groupe alkyle de 1 à 8 atomes de carbone, un groupe aralkyle de 7 à 8 atomes de carbone, ou un groupe aryle de 6 à 8 atomes de carbone ; n est un entier de 1 à 4 ; est un entier égal à 0 ou 1; et A et B sont chacun un groupe carbonyle, un groupe sulfonyle, un groupe bivalent dérivé d'un hydrocarbure aliphatique, un groupe bivalent dérivé d'un hydrocarbure aliphatique comprenant dans la chaîne principale au moins un élément choisi parmi un hétéroatome, un groupe carbonyle, un groupe sulfonyle, une liaison ester et un cycle aromatique ; ou un groupe bivalent dérivé d'un composé hydrocarboné aromatique préparé par liaison de deux hydrocarbures aromatiques par l'intermédiaire d'au moins un élément choisi parmi un hétéroatome, un groupe carbonyle, un groupe sulfonyle, une liaison ester, un alkylène et un hydrocarbure aliphatique comprenant un hétéroatome dans la chaîne principale. X preferably has the following formula (IV):

wherein R and R ', which may be the same or different, are each a hydrogen atom, a halogen atom, an alkyl group of 1 to 8 carbon atoms, an aralkyl group of 7 to 8 carbon atoms, or an aryl group of 6 to 8 carbon atoms; n is an integer of 1 to 4; is an integer equal to 0 or 1; and A and B are each a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, a divalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group a sulfonyl group, an ester linkage and an aromatic ring; or a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from heteroatom, carbonyl group, sulfonyl group, ester linkage, alkylene and hydrocarbon aliphatic compound comprising a heteroatom in the main chain.

 In addition, the divalent functional group represented by B in formula (IV) is preferably the sulfonyl group.

 In addition, the divalent functional group represented by X in formulas (I) to (III) is preferably derived from a divalent group selected from the group consisting of alkylene, oxyalkylene, thioalkylene, sulfinylalkylene and sulfonylalkylene groups each having 1 to 16 carbon atoms.

 The aforementioned second object of the present invention can be achieved by a thermosensitive recording material comprising a support on which is formed a thermosensitive coloring layer comprising a leuco dye and a color developer which is capable of initiating the formation of a color in the leuco dye upon the application of heat, the color developer comprising a composition containing at least two aromatic carboxylic acids selected from the group consisting of aromatic carboxylic acids having the formulas (I), (II) and (III) described above.

 The composition according to the present invention comprises at least two aromatic carboxylic acids selected from the group consisting of aromatic carboxylic acids represented by formulas (I), (II) and (III) above.

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 The reasons why the above-mentioned aromatic carboxylic acid composition is capable of giving good plasticizer resistance and good oil resistance to the colored images formed in the thermosensitive recording material are not yet clear, but it is believed that it is the following: (1) The composition of the present invention has excellent color development ability because the aromatic carboxylic acid of formula (I), (II) or (III) contained in the composition is a strong substituted acid by an electron attracting group.

 (2) The solubility of the above composition in non-volatile solvents such as oils and plasticizers can be reduced. This is because the molar mass of each aromatic carboxylic acid is increased by the presence in the molecule of two or more aromatic carboxylic acids.

The composition containing at least two aromatic carboxylic acids according to the present invention is new. This composition can be obtained by an esterification reaction between the anhydride of trimellitic acid and an alcohol, for example according to the following reaction scheme:

More specifically, by the above-mentioned reaction, the composition of the present invention is obtained in the form of a mixture of at least two aromatic carboxylic acids whose carboxyl groups are located at different positions, that is to say isomers. Thus, a composition containing the aromatic carboxylic acids of formula (I) and (II) can be obtained; a composition containing the aromatic carboxylic acids of formula (II) and (III); a composition containing the aromatic carboxylic acids of formula (I) and (III); and a composition containing the aromatic carboxylic acids of formula (I), (II) and (III). All of the above compositions can be used as color developer in the thermally sensitive recording material. If necessary,

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 the composition can be separated into the abovementioned isomers, for example by recrystallization or by chromatography.

 Specific examples of the divalent functional group represented by X in formulas (I), (II) and (III) include alkylene, oxyalkylene, dioxyalkylene, trioxyalkylene, oxoalkylene, dioxoalkylene, trioxoalkylene, thioalkylene, dithioalkylene, trithioalkylene, sulfinylalkylene, disulphinylalkylene groups. , trisulfinylalkylene, sulfonylalkylene, disulfonylalkylene, trisulfonylalkylene, hydroxyalkylene, dihydroxyalkylene, trihydroxyalkylene, sulfonyldioxyalkylene, disulfonyldioxyalkylene, trisulfonyldioxyalkylene, carbonyldioxyalkylene, dicarbonyldioxyalkylene, tricarbonyldioxyalkylene, carbamoylalkylene, dicarbamoylalkylene and tricarbamoylalkylene, each having 1 to 16 carbon atoms.

In addition, examples of the divalent functional group represented by X in formulas (I), (II) and (III) are as follows:

In the formulas (IV) to (VII), R and R ', which may be the same or different, are each a hydrogen atom, a halogen atom, an alkyl group of 1 to 8 carbon atoms, a group aralkyl of 7 or 8 carbon atoms or aryl group of 6 to 8 carbon atoms; n is an integer of 1 to 4.

 Specific examples of the divalent group represented by A in formulas (IV) and (VI) above include alkylene, oxyalkylene, dioxyalkylene, trioxyalkylene, oxoalkylene, dioxoalkylene, trioxoalkylene, thioalkylene, dithioalkylene, trithioalkylene, sulfinylalkylene, disulphinylalkylene,

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 trisulfinylalkylene, sulfonylalkylene, disulfonylalkylene, trisulfonylalkylene, hydroxyalkylene, dihydroxyalkylene, trihydroxyalkylene, sulfonyldioxyalkylene, disulfonyldioxyalkylene, trisulfonyldioxyalkylene, carbonyldioxyalkylene, dicarbonyldioxyalkylene, tricarbonyldioxyalkylene, carbamoylalkylene, dicarbamoylalkylene and tricarbamoylalkylene, each having 1 to 16 carbon atoms.

 With respect to B in the formulas (IV) and (V) above, m is an integer equal to 0 or 1. When m is an integer equal to 1, specific examples of the group represented by B in the formulas ( IV) and (V) are an oxygen atom, a carbonyl group, a sulfur atom, a sulfinyl group, a sulfonyl group, a sulfonyloxy group, a carbonyloxy group, a carbonylamino group, a urea group, a hydrazinocarbonyl group. , a hydrazinosulfonyl group, a phenylene group, a biphenylene group, a xylylene group, - (H3C) 2C ### C (CH3) 2- and -O2S ### SO2-.

 In addition, a divalent group represented by B in the formulas (IV) and (V) may be chosen from alkylene, oxyalkylene, dioxyalkylene, trioxyalkylene, oxoalkylene, dioxoalkylene, trioxoalkylene, thioalkylene, dithioalkylene, trithioalkylene, sulfinylalkylene, disulphinylalkylene and trisulfinylalkylene groups. sulfonylalkylene, disulfonylalkylene, trisulfonylalkylene, hydroxyalkylene, dihydroxyalkylene, trihydroxyalkylene, sulfonyldioxyalkylene, disulfonyldioxyalkylene, trisulfonyldioxyalkylene, carbonyldioxyalkylene, dicarbonyldioxyalkylene, tricarbonyldioxyalkylene, carbamoylalkylene, dicarbamoylalkylene and tricarbamoylalkylene, each having 1 to 16 carbon atoms.

For example, when the bivalent group X in the formulas (I), (II) and (III) is C 2 H 4, represented for convenience by Example 1, a composition containing at least two aromatic carboxylic acids can be obtained. selected from the group consisting of the following 3 isomers of formula (1-1), (1-11) and (1-III):

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Other examples of the bivalent group X are shown in Table 1 and in each case a composition containing at least two aromatic carboxylic acids selected from the group consisting of the three isomers represented by formulas similar to formulas (1-1) to (1-III).

-C3Ho- (2) -CaHs (3) -CaH.o# (4) -CaHia# ( 5 ) -C7H,4- (6) -clou20- ( 7 ) CH3 1 -CH2CCHi- (8) -CzH,OH4- (9) CH3 --CZN(OCzH4- (10) # C2H4(OC2H4)3# (11) -CZHafpH4)s- (12) -C3HepCli- (13) 0 Hs(aC3Hah- (14) -CH2CCH2- (15) -CH..SC2H.- (16) yH4SHaSH4- ( 17 ) -CHeSCaHe# (18) -CZHSSC2H4- (19) 0 O O - ( 2 0 ) ^C2H4SH4SH { 21 ) Table 1

-C3Ho- (2) -CaHs (3) -CaH.o # (4) -CaHia # (5) -C7H, 4- (6) -clou20- (7) CH3 1 -CH2CCHi- (8) -CzH, ## STR5 ## (15) -CH 2 SO 4 - (16) y H 4 SHaSH 4 - (17) -CHeSCaHe # (18) -CZHSSC 2 H 4 - (19) OO - (20) C 2 H 4 SH 4 SH (21)

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0 00 -C3H6SC3H6- ( 2 2 ) -CH-S-S-CsH# (2 ) 0 00 C2HaSC2H4' ( 2 4 ) -C2H"SC2H..SC2H,,- (25) 0 O 0 00 "CaHsSC3Hs- (26) -C2H4-S-S-GzH4- (27) 00 OH OH CH2 HCHZ- (28) -C2H4CHCHZ-- ( 2 9 ) -C2H..O-@--@-OC2H..- ( 30 ) -C2H40- ) rCH2 ( ) r-OC2H, ( 31 ) #-\ CH # -CZH4p--Lr-Ç-( )-OC=H4 ( 32 ) CH HgC \# CH3 CZH40 0 o OCZH4"' ( 3 3 ) CH3 H3C CH3 -C2H >àHOCH,- ( 3 4 ) /-*#' '##t CH3 H3C CH3 Table 1 (continued)

## STR0000 ## -C 2 H 4 -S-G 2 H 4 - (27) CH 2 HCH 2 - (28) -C 2 H 4 CHCH 2 - (2 9) -C 2 H 2 O - - - - - OC 2 H - (30) - C 2 H 40 -) CH 2 () ## STR5 ## ## STR2 ## ## STR2 ## ## STR2 ## C2H> toHOCH, - (3 4) / - * # ''## t CH3 H3C CH3

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CH3 --CzH,O Ç O OC2H4 ( 3 5 ) /*-*#' CH3 '##( v rl3 Br C3 ber . # . ÇH3/ # . ÇH3/ # -CZH,o-ç--( ( ) -ç-< t ) roC2H,- (36) CH3 CH 3 OCH2CH2O )-oC<<-- (37) -C2H40-@-S02-@-OC2H.- ( 38) -C:H<0'-)-S02-)-OC2H,# (38j -C2H40-@-SOZ OC2H4# (39) H3C CH3 -C2H40 SOZ OCZH4- (40) H3C CH3 CZH4Q SZ ./ C2H4 (4i) H3C CH3 Table 1 (continued)

## STR3 ## ## STR2 ## (## STR2 ## ## STR2 ##, ## STR2 ## ## STR2 ## wherein R 1 is CH 2 CH 2 CH 3 CH 2 OCH 2 CH 2 O - (C 1 -C) - (37) -C 2 H 4 O - SO 2 - O - CO 2 H - (38) - C: H (O -) -SO 2 -) - OC 2 H, # (38) -C 2 H 4 O - SO 2 OC 2 H 4 (39) H 3 C CH 3 -C 2 H 4 SO 2 OCZH 4 - (40) H 3 C CH 3 C 2 H 4 SZ 2 H 4 (4i) H 3 C CH 3

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Br 8r -C'H' frSO'OC2H'- (42) Br Br -C20->-S02C3H6S02-S)-OC2# ( 4 3 ) -CzHO-QSOCHSOzCzHSO#.OCzH# ( 4 4 ) -C2H,OS-S-)-OC2H,# ( 4 5 ) -C2H..O-@--S-@-OC2H,,- ( 4 6 ) -C20-(-0-)-OC2H# ( Q 7 ) -C:H,0---OC2H.- ( 4 8 ) 0 0 #CHOO/'H.-CNH#O-OCzH-- t 4 g ) NHC-C6H,,-CNH Q 0 0 pC2H4-. (50) Table 1 (continued)

## STR2 ## ## STR2 ## ## STR2 ## ## STR2 ## ## STR2 ## S -) - OC2H, # (4 5) -C2H ... O - @ - S - @ - OC2H ,, - (46) -C20 - (- O -) - OC2H # (Q 7) -C: ## STR2 ## ## STR2 ## ## STR1 ## ## STR2 ## (50)

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0 0 ---C2H40-( ) --NHC-( ( J ?---CNH- ) rOC2t I- (51) NHS \O/ NH -H40-<Q; A NH--@-NH 0 0 \Qj- C2H4- (52) -HZC--D-CH2- (53) -H2c-e CH2- (54) -H2C-()-CH2- ( 53 ) ~h2C-(Q> ( 54 ) -H4C2( ) i-C2H4- (55) # C2H4O# (Q/-OC2H4# (56) --<(>--;>-- (57) --@--CH2-@- (58) CH H3C CH3 --@-ç ( 5 9 ) - >y H31(j (60) CH3 60 ) CW3 \#/ CH3 H3C CH3 -B Br HjC CH3 CH3 8r, \#, CH3 -<0>~9-<Q>- (61) 0 ç 0 (62) H3C CH3 CH3 Br )- CH3-< Br Table 1 (continued)

## STR2 ## ## STR1 ## ## STR2 ## ## STR2 ## Q1-C2H4- (52) -HZC-D-CH2- (53) -H2c-e CH2- (54) -H2C- () - CH2- (53) -H2C- (Q> (54) -H4C2 ( ) ## STR2 ## ## EQU1 ## ## STR3 ## where: ## STR5 ## ## STR2 ## (61) 0 ç 0 (62) H3C CH3 CH3 Br) - CH3- <Br

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ru ru OCH2CH2O OHaOHaO/-- (63) # o <S\- (64) CHa éH3 Vry CH3 CH3 #- \#. Table 1 (continued)

## STR6 ## ## STR2 ## ## STR2 ## ## STR2 ##

# (Q) -SO2-Q) # (65) ~ (Q / S 2V- / (66) H3C CH3 Han CH3 SO2 (67) # <O> ~ s02D} # (68) Hac CH3 Br Br SO2 -CO - (69) -O) -SO, C 3 SO 3 - ## STR2 ## 0) -0 -:)) - (741 - (: - (; - - (75) - @ - NHë-C4He-ëNH - @ - (76)

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-& NHC-C4He-CNH * & (77) (77) #(O)~NH v3/ nh \O/ # (78) NHC-<Q>-CNH NHC# ô (O)~NH - (791 -))- (80) "~ (eu
Lorsque la composition d'acides carboxyliques aromatiques représentés par les formules (I) à (III) décrite ci-dessus est contenue dans la couche colorante thermosensible, la quantité de composition est de préférence comprise entre 1 et 10 g/m2, de façon plus préférable entre 1 et 5 g/m2, en matière sèche. Table 1 (continued)

## STR1 ## )) - (80) "~ (had
When the aromatic carboxylic acid composition represented by the formulas (I) to (III) described above is contained in the heat-sensitive coloring layer, the amount of composition is preferably between 1 and 10 g / m 2, more preferably preferably between 1 and 5 g / m2, in dry matter.

 The aforementioned basic dye precursors can be used as the leuco dyes alone or in combination with the color developer in the thermosensitive coloring layer. All leuco dyes that are conventionally employed in heat-sensitive recording materials can be used in the present invention.

 Specific examples of leuco dyes are: 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-6-methyl-7- anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-butylamino-6-methyl-7-anilinofluorane,

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 3-N-methyl-N-propylamino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-propylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-amylamino-6 methyl-7-anilinofluorane, 3-N-ethyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamylamino-6-methyl-7-anilinofluorane, 3-N- hexyl-N-isoamylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-furanylmethylamino-6-methyl-7- anilinofluorane, 3-diethyl-N-butylamino-7- (2'-fluoroanilino) fluorane, 3-pyrrolidyl-7-dibenzylaminofluorane, 3-bis (diphenylamino) fluorane, 3-diethylamino-7- (2'-diethylamino), chloroanilino) fluoran, 3-diethylamino-6-chloro-7-anilinofluorane, 3-dibutylamino-7- (2'-chloroanilino) fluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl- 7-chlorofluorane, 3-N-methyl-N-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-butylam ino-7- (2'-chloroanilino) fluoran, and 3-diethylamino-6-ethoxyethyl-7-anilinofluorane.

 The composition containing the aromatic carboxylic acids according to the present invention can be used alone as a color developing agent in the thermally sensitive recording material. The above composition can also be used in combination with conventional color developers. In this case, the composition of the present invention may also serve as a sensitizer.

 Specific examples of conventional color developer materials for use in the present invention are: 4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-sec-butylidenebisphenol, 4 , 4'-isopropylidenebis (2-tert-butylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2- (3,4-dihydroxyphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide,

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 4- [p- (p-methoxyphenoxy) ethoxy] salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, monobenzyl ester of phthalic acid, 4,4 ' cyclohexylidenebisphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2) methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexyl) butane, 4,4'-thiobis (6-tert-butyl-2-methylphenol), 4,4 bisphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4-isopropyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl, stearyl gallate, 1,3-bis (4-hydroxyphenylthio) propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N-diphenylthiourea, N, N-di ( m-chlorophenyl) thiourea, salicylanilide, 5-chlorosalicylanilide, bis (4-hydroxyphenyl) methyl acetate, bis (4-hydroxyphenyl) benzyl acetate 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 2,2'-diallyl-4,4'-diphenolsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, 4,4'-thiobis (2-methylphenol) and 4,4'-thiobis ( 2-chlorophenol).

 According to the present invention, the thermosensitive coloring layer may further comprise various heat-sensitive substances such as a heat-sensitivity-improving agent and a lubricant. In this case, the substance

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 thermosensitive can be used alone or in combination.

 Examples of heat-sensitive substances are: fatty acids such as stearic acid and behenic acid; fatty amides such as stearamide and palmitamide; metal salts of fatty acids such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate; and p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, p-benzyloxynaphthalene, phenyl p-naphthoate, phenyl 1-hydroxy-2-naphthoate, 1-hydroxy-2-naphthoate and the like. methyl, diphenyl carbonate, benzyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2-bis (4-methylphenoxy) ) ethane, 1,4-diphenoxybut-2-ene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthiobut-2-ene, 1,3 bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide, 1,1-diphenylethanol 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, Noctadecylcarbamoylben benzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate and bis (4-chlorobenzyl).

 In preparing the heat-sensitive recording material of the present invention, not only can the color developer be used as the aforementioned aromatic carboxylic acid composition, leuco dye and hot melt, but also other substances used as constituents of conventional thermosensitive recording materials. For example, various binders can be used to bind the substances constituting the thermosensitive coloring layer to the support. These binders can be used singly or in combination.

 Specific examples of binders for use in the thermosensitive coloring layer include water-soluble polymers such as polyvinyl alcohol, modified polyvinyl alcohol, starch and starch derivatives, cellulose such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, poly (sodium acrylate), polyvinylpyrrolidone, acrylamide-acrylic ester copolymer, acrylamide-acrylic ester-methacrylic acid terpolymer, alkaline salts of styrene-maleic anhydride copolymers,

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 alkali metal salts of isobutylene-maleic anhydride copolymers, polyacrylamide, modified polyacrylamide, methyl ether-vinyl-maleic anhydride copolymer, carboxy-modified polyethylene, vinyl alcohol-acrylamide block copolymer, melamine-formaldehyde resin, ureaformaldehyde resin, sodium alginate, gelatin, and casein; emulsions such as emulsions of polyvinyl acetate, polyurethane, styrene-butadiene copolymer, styrene-butadiene-acrylic copolymer, polyacrylic acid, polyacrylate, polymethacrylate, vinyl chloride-vinyl acetate copolymer poly (butyl methacrylate), polyvinyl butyral, polyvinyl acetal, and ethylene-vinyl acetate copolymer.

 If necessary, the aforementioned binders can be cured by the addition of a crosslinking agent (curing agent). In this case, a crosslinking agent (curing agent) capable of reacting with the binders, for example glyoxal derivatives, methylol derivatives, epichlorohydrin derivatives, epoxy compounds and aziridine compounds, may be used.

 In addition, the thermosensitive coloring layer may also comprise a pigment.

 Examples of pigments for use in the thermosensitive coloring layer are finely divided inorganic particles of silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, calcined kaolin, talc, and surface-treated silica; and finely divided organic particles of a urea-formalin resin, a styrene-methacrylic acid copolymer, a polystyrene resin, a vinylidene chloride resin, a styrene-acrylic copolymer, and various types of small hollow spherical particles of plastics material.

 The thermosensitive recorder material of the present invention may further comprise a protective layer which is deposited on the thermosensitive coloring layer to improve the head contact properties, i.e., the contact properties of the thermosensitive record material with a thermal head, to enhance the storage stability of recorded images, and to improve the quality of the writing and printing of the recording material.

 The protective layer may contain a pigment, a binder, a crosslinking agent and a lubricant. The same pigments, binders, crosslinking agents and lubricants (hot melt substances) as those described above can be used for the formation of the protective layer. With regard to each of these substances, such as the pigment or the binder, one can use a single constituent type

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 or two or more types of components in combination.

 The thermosensitive recording material of the present invention may further comprise a bottom layer interposed between the support and the thermosensitive coloring layer. The primer, comprising as main components a pigment and a binder, can serve as a thermal insulation layer. Thus, thanks to the presence of the primer, the heat energy supplied to the thermosensitive recorder material by the thermal head can be used effectively, which improves the heat sensitivity of the recording material. With regard to the pigment or binder to be used in the primer, the aforementioned pigments or binders can be used independently, alone or in combination. In particular, it is desirable to use spherical hollow plastic particles as the pigment in the primer.

 Spherical hollow plastic particles for use in the present invention include a thermoplastic resin that forms the shell of each hollow particle. Hollow particles in the expanded state contain air or other gases.

 The average particle diameter (outer diameter) of the hollow particles is preferably between about 0.2 and 20 m. When the average particle size of the hollow particles is within the above range, there is no production problem, because the void fraction of the hollow particles can be freely determined. In addition, the smoothness of the surface of the primer layer obtained by coating is not excessively reduced. As a result, the adhesion of the surface of the thermosensitive recording material to the thermal head does not decrease, and thus a deterioration of the thermal sensitivity of the recording material can be avoided. In addition, hollow particles classified in narrow particle size are preferably used in the bottom layer.

 The void fraction of the spherical hollow particles to be used in the basecoat is preferably at least 40%, and more preferably at least 90%, with respect to the thermal insulation effect. When the void fraction is within the aforementioned range, a sufficient thermal insulation effect of the bottom layer can be obtained, which makes it possible to prevent the thermal energy supplied by the thermal head from escaping through the support of the thermosensitive recording material. As a result, the effect of improving the thermal sensitivity is not impaired.

 In the present invention, the void fraction of the spherical hollow plastic particles to be used in the basecoat is expressed by the

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following formula: void fraction (%) internal diameter of hollow particles x 100 void fraction (%) outer diameter of hollow particles
Specific examples of the thermoplastic resin used for forming the shell of the hollow particles are polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester acrylic), polyacrylonitrile, polybutadiene, and copolymer resins comprising the monomers used in the aforementioned resins. Among these thermoplastic resins, it is preferable to use in the present invention a copolymer resin comprising as main constituent vinylidene chloride or acrylonitrile.

 The binder resin for the formation of the aforesaid basecoat can be suitably selected from water-soluble polymers and aqueous emulsions of conventional polymers.

 Specific examples of binders for use in the basecoat are water-soluble polymers such as polyvinyl alcohol, starch and starch derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, and the like. carboxymethylcellulose, methylcellulose and ethylcellulose, poly (sodium acrylate), polyvinylpyrrolidone, acrylamide-acrylic ester copolymer, acrylamide-acrylic ester-methacrylic acid terpolymer, alkaline salts of styrene-maleic anhydride copolymers, salts alkalines of isobutylene-maleic anhydride copolymers, polyacrylamide, sodium alginate, gelatin, and casein; aqueous polymer emulsions comprising latices such as a styrene-butadiene copolymer and a styrene-butadiene-acrylic copolymer, and emulsions such as a vinyl acetate resin, a vinyl acetate-acrylic acid copolymer, a styrene-acrylic ester copolymer, a acrylic ester resin and a polyurethane resin.

 In the basecoat to be used in the present invention, the above-mentioned spherical hollow plastic particles and binder resin may be used in combination with auxiliary additives such as filler, hot melt, surfactant and an agent for to avoid the development of coloring by the application of pressure, which are used in conventional thermosensitive recording materials. Specific examples of fillers and hot melt materials for use in the basecoat are the

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 same as those mentioned for the formation of the thermosensitive coloring layer. In addition, when the primer contains spherical hollow particles of plastic, it is recommended to incorporate an inorganic pigment in the primer to improve the properties of contact with the head.

 In addition, in the present invention, an intermediate layer comprising a pigment, a binder and a hot melt substance may be interposed if necessary between the primer layer and the thermosensitive coloring layer.

 The thermosensitive recorder material of the present invention may further include a backcoating layer provided on the backside surface of the backing, opposite the heat-sensitive coloring layer with respect to the backing. The back coating layer comprises the same pigments, binders and lubricants (hot melt substances) as those indicated above.

 As a support for the heat-sensitive recording material, a plain paper sheet, such as acid paper or basic paper, and other support elements which can be coated with a coating liquid can be freely used. For example, a sheet of synthetic paper and a polymer film can be used as a support.

 The thermosensitive recorder material of the present invention is applicable in all fields that utilize conventional thermosensitive recording materials. For example, thermally sensitive recording material can be used as facsimile paper, point of sale labels for food, bar code labels for industrial applications, unlicensed type thermo-sensitive adhesive labels, ticket paper, ticket paper. magnetic, CAD paper, and transparent thermosensitive films.

 Other features of this invention will become apparent from the following description of exemplary embodiments, which are given for purposes of explanation of the invention and are not intended to limit it.

Preparation Example 1 Synthesis of composition 38 of carboxylic acids using the bivalent group X represented by # 38 of Table 1
A mixture of 84.5 g (0.25 moles) of bis [4- (2hydroxyethoxy) phenyl] sulfone, 114.1 g (0.60 moles) of trimellitic acid anhydride and 151.5 g (1.50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to

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 carry out the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 163.0 g of white crystals were thus obtained with a yield of 90%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 95.3% according to a high performance liquid chromatography (HPLC) analysis and its melting point was 195-212 C. The corresponding reaction product was identified as the intended composition by NMR deH.

 Δ (ppm) = 13.50 (br), 8.22 (4H, t), 7.79 (6H, t), 7.17 (4H, d), 4.63 (4H, brs), 4.44 (4H, brs).

Preparative Example 2 Synthesis of composition 40 of aromatic carboxylic acids using divalent group X represented by # 40 of Table 1
A mixture of 91.5 g (0.25 mol) of bis [3-methyl-4- (2-hydroxyethoxy) phenyl] sulfone, 114.1 g (0.60 mol) of trimellitic acid and 151.5 g (1.50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 178.1 g of white crystals were thus obtained with a yield of 95%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 96.1% (according to HPLC analysis) and its melting point was 213-232 C. The corresponding reaction product was identified as the intended composition by 1 H NMR analysis. .

 # (ppm) = 8.24 (4H, t), 7.85 (2H, d), 7.77 (4H, d), 7.22 (2H, d), 4.70 (4H,

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 t), 4.38 (4H, t), 2.20 (6H, s).

Preparation Example 3 Synthesis of composition 32 of aromatic carboxylic acids using the divalent group X represented by # 32 of Table 1
A mixture of 79.1 g (0.25 mol) of 2,2'-bis [4- (2hydroxyethoxy) phenyl] propane, 114.1 g (0.60 mol) of trimellitic acid and 151.5 g (1.50 mol) triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 131.3 g of white crystals were thus obtained with a yield of 78%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 87.2%, according to gel permeation chromatography (GPC) analysis. Despite the ambiguity of its melting point, the corresponding reaction product was identified as the intended composition by NMR analysis of H.

 8 (ppm) = 13.53 (br), 8.20 (4H, t), 7.77 (2H, t), 7.77 (4H, d), 7.12 (4H, d), 6 , 86 (4H, d), 4.54 (4H, brs), 4.24 (4H, brs), 1.56 (6H, s).

Preparation Example 4 Synthesis of composition 53 of aromatic carboxylic acids using the bivalent group X represented by # 53 of Table 1
A mixture of 34.5 g (0.25 mol) of 1,4bis (hydroxymethyl) benzene, 114.1 g (0.60 mol) of trimellitic acid anhydride and 151.5 g was suspended. g (1.50 mol) triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to room temperature.

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 pH less than or equal to 2.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 125.8 g of white crystals were thus obtained with a yield of 96%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 94.2% (according to HPLC analysis) and melting points were observed at 191 ° C. and 249 ° C. The corresponding reaction product was identified as the intended composition by NMR analysis. from 'H.

 # (ppm) = 8.21 (4H, t), 7.81 (2H, t), 7.48 (4H, s), 5.33 (4H, s).

Preparation Example 5 Synthesis of Composition No. 56 of aromatic carboxylic acids using divalent group X represented by # 56 of Table 1
A mixture of 49.6 g (0.25 mole) of 1,4-bis (2-hydroxyethoxy) benzene, 114.1 g (0.60 mole) of trimellitic acid anhydride, and 151 g (0.60 mole) was suspended. 5 g (1.50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 144.0 g of pale yellow-white crystals were thus obtained with a yield of 99%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 92.2% (according to HPLC analysis) and its melting point was 218 C. The corresponding reaction product was identified as the intended composition by 1H NMR analysis. δ (ppm) = 13.58 (br), 8.20 (4H, t), 7.85 (2H, t), 6.91 (4H, s), 4.54 (4H, s), 4 , (4H, brs).

Preparation Example 6 Synthesis of composition 16 of aromatic carboxylic acids using the bivalent group X represented by n 16 of Table 1
A mixture of 30.5 g (0.25 mol) of bis (2-hydroxyethyl) sulfide, 114.1 g (0.60 mol) of trimellitic acid anhydride and

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 151.5 g (1.50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 96.1 g of pale yellow-brown crystals were thus obtained with a yield of 76%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 95.0% (according to HPLC analysis) and its melting point was 166 C. The corresponding reaction product was identified as the intended composition by NMR analysis of H.

 Δ (ppm) = 13.46 (br), 8.21 (4H, t), 7.78 (2H, t), 4.42 (4H, t), 2.93 (4H, t).

PREPARATION EXAMPLE 7 Synthesis of Composition # 3 of aromatic carboxylic acids using the divalent group X represented by # 3 of Table 1
A mixture of 22.5 g (0.25 mol) of 1,4-butanediol, 114.1 g (0.60 mol) of trimellitic acid anhydride and 151.5 g (1, 50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 109.8 g of pale yellow-white crystals were thus obtained with a yield of 93%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 97.3% (according to HPLC analysis) and melting points were observed at 99 C, 183 C and 242-258 C. The product was identified

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 corresponding reaction as the intended composition by NMR analysis of H.

 # (ppm) = 13.45 (br), 8.25 (2H, d), 8.15 (2H, m), 7.79 (2H, t), 4.31 (4H, brs), 1.81 (4H, brs).

Preparation Example 8 Synthesis of Composition No. 7 of aromatic carboxylic acids using divalent group X represented by # 7 of Table 1
A mixture of 43.6 g (0.25 mol) of 1,10-decanediol, 114.1 g (0.60 mol) of trimellitic acid anhydride and 151.5 g (1, 50 mol) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water was added dropwise to the reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 131.4 g of white crystals were thus obtained with a yield of 94%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 97.1% (according to HPLC analysis) and melting points were observed at 160 ° C, 185 ° C and 226 ° C. The corresponding reaction product was identified as the composition intended by NMR analysis of H.

 # (ppm) = 13.48 (br), 8.19 (4H, m), 7.77 (2H, t), 4.23 (4H, t), 1.63 (4H, brs), 1.28 (12H, s).

Preparation Example 9 Synthesis of aromatic carboxylic acid composition No. 10 using the divalent group X represented by # 10 of Table 1
A mixture of 37.5 g (0.25 mol) of triethylene glycol, 114.1 g (0.60 mol) of trimellitic acid anhydride and 151.5 g (1.50 mol) was suspended. ) of triethylamine in a mixed solvent consisting of 150 g of tetrahydrofuran and 50 g of dimethylformamide in a reaction vessel. The mixture was heated at about 83 ° C under reflux to effect the reaction for 3 hours.

 After cooling, 100 ml of water were added dropwise to

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 reaction mixture. The resulting mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise to the mixture to bring it to pH 2 or below.

 The above mixture separated into two layers at rest. The organic layer was washed with water until crystallization of the reaction product. 66.8 g of pale yellow crystals were thus obtained with a yield of 50%. This reaction product was a composition consisting of three types of isomers. The purity of the composition was 90.8% (according to HPLC analysis) and melting points were observed at 163 C 214-234 C. The corresponding reaction product was identified as the intended composition by NMR of H.

 # (ppm) = 13.53 (br), 8.17 (4H, t), 7.77 (2H, t), 4.37 (4H, t), 3.71 (4H, t), 3 , 58 (4H, s).

Example 1 Preparation of the heat-sensitive recording material n 1
The component mixtures below were dispersed separately in a porcelain ball mixer to prepare a liquid A, a liquid B, a liquid C and a liquid D.

Liquid A
Parts by weight 3-N, N-dibutylamino-6-methyl-7-anilinofluorane 10% aqueous solution of polyvinyl alcohol Water 30 Liquid B
Mass Parts Composition No. 38 (prepared in Preparation Example 1) 10% aqueous polyvinyl alcohol solution Water 30 Liquid C
Mass Parts Silica Gel (Trade Mark "P257", produced by Mizusawa Industrial Chemicals, Ltd) 10% aqueous polyvinyl alcohol solution 10 Water 30

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Liquid D
Parts by weight Zinc Stearate 10 10% aqueous solution of polyvinyl alcohol 10 Water 30
A mixture of the components below was stirred and dispersed in a dispersion mixer to prepare a liquid E.

Liquid E
Mass parts Small unexpanded hollow plastic particles (solid content: mass%, average particle diameter: 3 m, void fraction:%) 40 Styrene-butadiene copolymer latex 10 Water 50 Formation of the primer
Liquid E and liquid C were mixed at a mass ratio of 2: 1 to prepare a coating liquid for the primer. The coating liquid for the basecoat thus prepared was applied to a sheet of paper. of high quality commercially available having a basis weight of 60 g / m2, serving as a support, then it was dried so as to have a deposited amount of 3 g / m2 dry matter, whereby a layer was formed background on the support.

Formation of the thermosensitive coloring layer
Liquid A, liquid B, liquid C and liquid D were mixed at a mass ratio of 1: 4: 4: 0.5 to prepare a coating liquid for the heat-sensitive coloring layer. The coating liquid for the thermosensitive coloring layer thus prepared was applied to the primer layer prepared previously, and then dried so as to have a deposited amount of leuco dye of 0.5 g / m 2 dry matter, thanks to to which a thermosensitive coloring layer has been formed on the primer layer.

 The surface of the thermosensitive coloring layer thus obtained was subjected to calendering by applying a pressure of 10 kg / cm 2.

 The heat-sensitive recording material No. 1 was thus obtained according to the present invention.

Example 2
The technique for the preparation of the heat-sensitive recording material No. 1 of Example 1 was repeated, except that the composition was replaced

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 No. 38 in the liquid B for the coating liquid for the thermosensitive coloring layer in Example 1 with the composition No. 40 prepared in Preparation Example 2.

 The heat-sensitive recording material No. 2 was thus obtained according to the present invention.

Example 3
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 with composition 32 prepared in Preparation Example 3

 The thermosensitive recording material No. 3 was thus obtained according to the present invention.

Example 4
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 53 prepared in Preparative Example 4

 The heat-sensitive recording material No. 4 was thus obtained according to the present invention.

Example 5
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 56 prepared in Preparative Example 5

 The thermosensitive recording material No. 5 was thus obtained according to the present invention.

Example 6
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 16 Prepared in Preparation Example 6

 The thermosensitive recording material n 6 was thus obtained according to the

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 present invention.

Example 7
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 3 Prepared in Preparation Example 7

 The thermosensitive recording material No. 7 was thus obtained according to the present invention.

Example 8
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 7 prepared in Preparative Example 8

 The heat-sensitive recording material No. 8 was thus obtained according to the present invention.

Example 9
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 by Composition No. 10 Prepared in Preparation Example 9

 The heat-sensitive recording material No. 9 was thus obtained according to the present invention.

Comparative Example 1
The technique for the preparation of thermosensitive recorder material No. 1 of Example 1 was repeated, except that composition No. 38 was replaced in the liquid B for the coating liquid for the thermosensitive coloring layer in FIG. Example 1 with 2,2-bis (4-hydroxyphenyl) propane, namely bisphenol A.

 Thus, the comparative heat-sensitive recording material No. 1 was obtained.

Measure the color density of the image
Each of the thermosensitive recording materials No. 1 to 9 according to the present invention, obtained in Examples 1 to 9, was charged with the material

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 Comparative heat recorder No. 1 obtained in Comparative Example 1 in a commercially available thin-film head printing test apparatus (manufactured by Matsushita Electronic Components Co., Ltd.), and images were formed on each recording material under the following conditions: the applied electrical power was 0.68 W / dot, the period for one line was 10 ms / line, the scanning density was 8 x 3.85 points / mm, and the pulse duration was 0.9 ms. In this way, image samples were prepared.

 The staining density of the image recorded on each image sample was measured using a McBeth densitometer.

 The results are shown in Table 2.

Evaluation of the storage stability of the recorded image 1. Testing of resistance to plasticizers
The image sample prepared above was overlaid with three commercially available vinyl chloride packaging sheets manufactured by Shin-Etsu Polymer Co, Ltd. Each sample was allowed to stand at 40 ° C with a load of 50 kg for 15 hours.

 After 15 hours, the staining density of the image was measured using the McBeth densitometer to evaluate plasticizer resistance.

 The results are also presented in Table 2.

2. Oil resistance test
After applying cottonseed oil to each image sample, the image sample was allowed to stand at 40 ° C. for 15 hours.

 After 15 hours, the staining density of the image was measured using the McBeth densitometer to evaluate the oil resistance.

 The results are also presented in Table 2.

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Table 2

<Tb>
<tb> Density <SEP> of <SEP> Density <SEP> of <SEP> staining <SEP> Density <SEP> of <SEP> staining
<tb> staining <SEP> at <SEP> after <SEP><SEP><SEP> testing <SEP> after <SEP><SEP> testing
<tb> stage <SEP> initial <SEP> to <SEP> plasticizers <SEP> resistance <SEP> to <SEP> oils
<tb> Example <SEP> 1 <SEP> 1.16 <SEP> 1.19 <SEP> 1.27
<tb> Example <SEP> 2 <SEP> 1.04 <SEP> 0.92 <SEP> 1.03
<tb> Example <SEP> 3 <SEP> 1.27 <SEP> 1.16 <SEP> 1.35
<tb> Example <SEP> 4 <SEP> 1.07 <SEP> 0.84 <SEP> 1.14
<tb> Example <SEP> 5 <SEP> 1.18 <SEP> 0.90 <SEP> 1.23
<tb> Example <SEP> 6 <SEP> 1.26 <SEP> 1.23 <SEP> 1.32
<tb> Example <SEP> 7 <SEP> 1.26 <SEP> 1.21 <SEP> 1.31
<tb> Example <SEP> 8 <SEP> 0.87 <SEP> 0.70 <SEP> 0.98
<tb> Example <SEP> 9 <SEP> 0.98 <SEP> 0.93 <SEP> 1.13
<tb> Example <SEP> 1.42 <SEP> 0.19 <SEP> 0.45
<tb> comparative <SEP> 1
<Tb>

From the results presented in Table 2 it can be seen that when the aromatic carboxylic acid composition represented by the formulas (I) to (III) according to the present invention is used as a color developer in the thermally sensitive recording material, the colored images formed in the recording material exhibit excellent storage stability, particularly with respect to plasticizer resistance and oil resistance.

Claims (8)

A composition comprising at least two aromatic carboxylic acids selected from the group consisting of aromatic carboxylic acids having the formulas (I), (II) and (III):

 in which X represents a carbonyl group; a sulfonyl group; a divalent group derived from an aliphatic hydrocarbon; bivalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage and an aromatic ring; a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage, an alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain.  2. Composition according to claim 1, wherein, in formulas (I) to (III), said divalent X functional group is represented by formula (IV):

 wherein R and R ', which may be the same or different, are each a hydrogen atom, a halogen atom, an alkyl group of 1 to 8 carbon atoms, an aralkyl group of 7 to 8 carbon atoms, or an aryl group of 6 to 8 carbon atoms <Desc / Clms Page number 33>  carbon; n is an integer of 1 to 4; is an integer equal to 0 or 1; and A and B are each a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, a divalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group a sulfonyl group, an ester bond and an aromatic ring, or a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage, an alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain.  The composition of claim 2 wherein in formula (IV) said divalent functional group represented by B is a sulfonyl group.  The composition according to claim 1, wherein, in formulas (I) to (III), said divalent functional group represented by X is derived from a divalent group selected from the group consisting of alkylene, oxyalkylene, thioalkylene, sulfinylalkylene and sulfonylalkylene each having 1 to 16 carbon atoms.  A heat-sensitive recording material comprising a support on which is formed a thermosensitive coloring layer comprising a leuco dye and a color developer capable of initiating the formation of a color in said leuco dye upon the application of heat, said developer color former comprising a composition containing at least two aromatic carboxylic acids selected from the group consisting of aromatic carboxylic acids having the formulas (I), (II) and (III):

<Desc / Clms Page number 34>  in which X represents a carbonyl group; sulfonyl group; a divalent group derived from an aliphatic hydrocarbon; bivalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage and an aromatic ring; a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage, an alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain.  The thermosensitive recording material according to claim 5, wherein, in formulas (I) to (III), said divalent functional group X is represented by formula (IV):

 wherein R and R ', which may be the same or different, are each a hydrogen atom, a halogen atom, an alkyl group of 1 to 8 carbon atoms, an aralkyl group of 7 to 8 carbon atoms, or an aryl group of 6 to 8 carbon atoms; n is an integer of 1 to 4; m is an integer of 0 or 1; and A and B are each a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, a divalent group derived from an aliphatic hydrocarbon comprising in the main chain at least one member selected from a heteroatom, a carbonyl group a sulfonyl group, an ester bond and an aromatic ring, or a divalent group derived from an aromatic hydrocarbon compound prepared by binding two aromatic hydrocarbons via at least one member selected from a heteroatom, a carbonyl group, a sulfonyl group, an ester linkage, an alkylene and an aliphatic hydrocarbon comprising a heteroatom in the main chain.  The thermosensitive recording material according to claim 6, wherein in formula (IV) said divalent functional group represented by B is a sulfonyl group.  The thermosensitive recording material according to claim 5, wherein, in formulas (I) to (III), said divalent functional group represented by X is derived from a divalent group selected from the group consisting of alkylene, oxyalkylene, thioalkylene, sulfinylalkylene and sulfonylalkylene each having 1 to 16 carbon atoms.